Hard metal wearing part with mixed oxide coating

Abstract

The wearing part, such as a cutting insert, is made from hard metal or cermet. A hard-material coating is applied on the base material. The coating includes a single-layer or multilayer mixed-oxide coat, predominantly comprising Al 2 O 3 , in which defined proportions of titanium oxide and boron oxide are dissolved or homogeneously distributed extremely finely. The wearing part is distinguished by a high wear resistance, which improves the service life, and a fine-grained structure and uniformity of the coat and by a highly economic application of the coat.

We claim:  
     
       1. A wearing part, comprising: 
       a base material selected from the group consisting of hard metal and cermet;  
       a hard-material coating on said base material, said coating having at least one mixed-oxide layer predominantly formed of Al 2 O 3  and substantially determining a wear of said hard-material coating, said mixed-oxide layer having a thickness of 0.5 to 10 μm, containing an addition of from 0.1 to ≦3% by weight of TiO 2  and 0.01 to 0.5% by weight of B 2 O 3 , and said addition being substantially dissolved and homogeneously distributed in the Al 2 O 3  phase.  
     
     
       2. The wearing part according to  claim 1 , wherein said base material and said hard-material coating are configured as a cutting insert. 
     
     
       3. The wearing part according to  claim 1 , wherein said hard-material coating is a single-layer mixed-oxide coating. 
     
     
       4. The wearing part according to  claim 1 , wherein said hard-material coating is a multilayer coating including said mixed-oxide layer. 
     
     
       5. The wearing part according to  claim 1 , wherein said multilayer coating is a mixed-oxide coat with a lamellar multilayer structure. 
     
     
       6. The wearing part according to  claim 5 , wherein said layers of said lamellar multilayer structure are interrupted by interlayers comprising the elements Ti and one or more elements selected from the group consisting of C, N, B, O and (Ti, Al) and one or more elements selected from the group consisting of C, N, B, and O and having a thickness from 0.05 to 1 μm. 
     
     
       7. The wearing part according to  claim 5 , wherein said layers of said lamellar multilayer structure are interrupted by interlayers comprises of Ti and one or more elements selected from the group consisting of C, N, B, and O, having a thickness from 0.05 to 1 μm, and said interlayers between individual mixed-oxide layers of said mixed-oxide coat contain, in addition to titanium, a member of the group consisting of carbon and nitrogen, boron and nitrogen, as a mandatory constituent and the respectively other members of the group as optional constituents. 
     
     
       8. The wearing part according to  claim 1 , which comprises an undercoat of at least one material selected from the group consisting of carbides, nitrides, carbonitrides, and borides disposed between said base material and said mixed-oxide layer and having a thickness from 1 to 15 μm. 
     
     
       9. The wearing part according to  claim 8 , wherein said undercoat is a multilayer coat. 
     
     
       10. The wearing part according to  claim 8 , which comprises a Ti (N, B) coat disposed between said undercoat and said mixed-oxide layer and having a thickness from 0.2 to 2 μm. 
     
     
       11. The wearing part according to  claim 1 , which comprises a further layer formed on said hard-material coating, said further layer comprising one or more hard materials of Me(C, N, B), and an optional minor proportion of oxide, and having a thickness from 0.5 to 3 μm. 
     
     
       12. The wearing part according to  claim 11 , wherein said further layer is a single-layer coating. 
     
     
       13. The wearing part according to  claim 11 , wherein said further layer is a multilayer coating. 
     
     
       14. The wearing part according to  claim 11 , which further comprises an additional mixed-oxide layer applied to said further layer. 
     
     
       15. The wearing part according to  claim 11 , wherein said additional mixed-oxide layer is a single-layer coating. 
     
     
       16. The wearing part according to  claim 11 , wherein said additional mixed-oxide layer is a multilayer coating. 
     
     
       17. The wearing part according to  claim 1 , wherein individual or all layers of said hard-material coating are CVD coatings deposited under standard pressure. 
     
     
       18. A wearing part, comprising: 
       a body of a base material selected from the group consisting of hard metal and cermet; and  
       a hard-material coating on said body of base material, said hard-material coating including  
       a multilayer mixed-oxide coat predominantly formed of Al 2 O 3 , having a thickness of 0.5 to 10 μm, and containing, substantially dissolved and homogeneously distributed in the Al 2 O 3 , phase, an addition of from 0.1 to ≦3% by weight of TiO 2  and 0.01 to 0.5% by weight of B 2 O 3 ; and  
       interlayers of a material selected from the group consisting of Ti(C, N, B, O) and (Ti, Al) (C, N, B, O) formed between individual layers of said multilayer mixed-oxide coat and having a thickness of 0.05 to 1 μm.  
     
     
       19. The wearing part according to  claim 18 , which further comprises an undercoat formed of at least one material selected from the group consisting of carbides, nitrides, carbonitrides, and borides, having a thickness of between 1 and 15 μm, and disposed between said base material and said mixed-oxide coat. 
     
     
       20. The wearing part according to  claim 18 , wherein said body and said coating together form a cutting insert.